When you talk top speed to most people, they usually start thinking in terms of horsepower. "If I had that turbo-nitrous 1300cc kit on my bike, I'd be doin' 200 mph for sure." Turn up the boost, stick in bigger nitrous jets, make the engine bigger, give it higher compression and beefier cams-it's easy to equate monstrous horsepower output with killer top speed.
But when you talk top speed to a racer like Sam Wheeler, the buzz word is drag. As in aerodynamic drag. His is a racing world dominated by phrases like boundary layer, rolling resistance, vortex generators and frontal area. An environment where bhp is important, but Cd (coefficient of drag: a mathematical term used to describe an object's overall aerodynamic drag; the lower the number, the more slippery the object) is king.
It's often noted that motorcycles are about as aerodynamically slippery as bricks-with the wide end facing forward. There are many hulking passenger cars available now with Cds that are a far lower than the best stock-bodied motorcycle numbers.
How bad are today's bikes? Consider this: A stock Kawasaki ZX-11 (the previous horsepower and top-speed king, 'til Honda's CBR1100XX came and spoiled the party) cranks out roughly 130 rear-wheel horsepower and will top out around 176 mph. Terry Kizer's Mr. Turbo ZX-11 that set the Sport Rider UFO top-speed record of 230 mph (albeit with gearing and space limitations) was probably cranking out upwards of 350 horsepower to get there.
An aerodynamics graduate class...
An aerodynamics graduate class at Caltech used the designing of Wheeler's streamliner as its thesis project, spending a full three weeks in the wind tunnel. The leading edge of the windscreen was made by Zero Gravity, for optical clarity.
But when Sam Wheeler first took his "EZ Hook" streamliner out to the salt flats for its first real top-speed shakedown run, he managed to blow through the traps at 270 mph--using a stock ZX-11 motor!
He returned the following year, the streamliner fitted with a modified motor out of his pal Doug Meyer's Bonneville record-setting ZX-11 (conservatively estimated to be cranking out around 160 horsepower), and upped his speed to the tune of 301 mph! To put things in perspective, the outright motorcycle speed record of 323 mph was set by a dual-engined, nitro-burning Harley that was claimed to be pumping out around 450 horsepower.
Wheeler's streamliner controls...
Wheeler's streamliner controls consist of standard Kawasaki ZX-7R tachometer, temp gauge, clutch and brake assemblies, along with a pneumatic shifter. The gauge on the right shows airbox pressure from the ram-air system; the two knobs on each side of the cockpit control on-board fire extinguishers.
"We're still in the planning stages on what type of motor setup we'll use this year, but we're pretty confident that with a little extra horsepower, we'll beat that record," says Wheeler. Anyone willing to bet against him? We aren't.
The genesis of this incredible project was hatched "over a bottle of scotch 10 years ago," recalls the soft-spoken Californian. But don't think for a minute that this was some wild scheme carried out by a bunch of bored engineers; Wheeler is one of the most experienced and knowledgeable Bonneville veterans around. His salt exploits date back to 1963 with a Bultaco 125, leading up to a record-setting 208.729- mph run on a Norton 750 in 1970 (!), using a modified external fuel tank from an F84 fighter jet for bodywork.
The drag chute is deployed...
The drag chute is deployed out of this trick "split" tailsection, which is operated pneumatically. Note the aircraft-quality construction, all fabricated by Wheeler in EZ Hook Inc.'s machine shop.
The biggest step with any streamliner project is sorting out the aerodynamic equation, and luckily Wheeler had some bright young minds on his side. "It's a long story, but basically my boss, Phelps Wood, was talking with Elliot Andrews, the head of the engineering department at Caltech, when he mentioned what I was doing," relates Wheeler. "And when Andrews asked the graduate student aerodynamics class if they were interested, five of them picked it up as their class thesis project." With Caltech's considerable technical facilities (including a complete wind tunnel) at their disposal, the students--with the help of teaching assistant Dennis Moor--enthusiastically began preliminary mock-ups.
One-eighth scale models of various shapes were tested in water (a cheaper method of aerodynamics testing) in order to pick out the best configuration. Then a quarter-scale model was further refined in the wind tunnel for three weeks.
There isn't much room to move...
There isn't much room to move around inside Wheeler's streamliner, even with a skinny editor, as this photo with yours truly inside shows. Definitely not for the claustrophobic.
When the students finally settled on a shape, Wheeler made a rough plug of the mold, taking it down to RD Boatworks in San Juan Capistrano, California, where Bob DeLong laid the bodywork. Using a carbon/foam/carbon composite sandwich for the necessary strength and light weight, the final assembly tips the scales at 47 pounds without paint and hardware. "A lot of people don't think weight is important at Bonneville, but you've only got a certain amount of distance to get up to speed, which means the acceleration of mass is an important part of the overall speed equation," reveals Wheeler. Funds for this elaborate construction were provided by Kawasaki.
Nearly all the fabrication and construction of chassis and suspension parts was performed at EZ Hook Inc.'s (a manufacturer of electronic test parts) machine shop by Wheeler. The front portion of the chassis is made with 1.25-inch by 0.090-inch wall 4130 chrome-moly steel tubing (as dictated by the rules), while the rear section is comprised of 1.0 x 2.0 x 0.125-inch wall aluminum tubing for less weight.
Due to aerodynamic and space...
Due to aerodynamic and space considerations, Wheeler devised this "total loss" cooling system using water-spray jets to keep both the coolant and oil radiators chilled.
A unique feature of the chrome-moly portion of the frame is its dual function as a pressurized nitrogen tank for operation of various components. A total capacity of 1000 cubic inches of pressurized gas operates the mechanism for deploying the drag chutes, the retractable side skids (for keeping the streamliner upright at slow speeds) and the pneumatic shifting system. A fail-safe switch for both tip-over and pressure loss deploys the drag chutes automatically.
Both front and rear suspension systems were built completely by Wheeler. The front suspension consists of two leading-link A-arms with pull-rod for steering, with a specially built hlins damper providing two inches of travel. Rear suspension is a dual trailing multilink parallelogram assembly, attached to another special two-inch-travel Ohlins shock.
Rear suspension consists of...
Rear suspension consists of a dual-trailing, multilink parallelogram system, with a specially built hlins shock offering only two inches of travel. The tank just aft of the tire is the total loss coolant reservoir.
The 18-inch front wheel is shod with a specially built Goodyear car dragster front tire with more plies to withstand the heat, while the rear tire is a "standard Bonneville racer" issue piece. The complete assembly stretches out to a 117-inch wheelbase, with a total weight of 983 pounds (with Wheeler in the cockpit).
Because of frontal area and internal space concerns, Wheeler devised a "total loss" water-cooling setup for the ZX-11 motor. Since the actual run-time is somewhat small, a heat exchanger sprayed by water jets deals with cooling both coolant and oil; Wheeler admits that with added horsepower, this system will be insufficient, and is already at work on a different solution.
Wheeler's desire for speed...
Wheeler's desire for speed is evident in this circa 1963 photo (note the cool background machinery), when the then-20-year-old drove this incomplete ("We didn't finish the rear cowl in time.") Bultaco 125-powered streamliner to a top speed of 92 mph.
And how does this projectile ride at 300-plus mph? You were expecting maybe a vibration-filled, wobbling, weaving, death ride that had your eyeballs bouncing in their sockets so much you could barely see? "Actually, if the salt's smooth and there are no sidewinds, it's a comfortable ride," says Wheeler matter-of-factly, although he admits that "when the salt's soft, ruts will form that'll cause a little headshake sometimes. If there are sidewinds, you have to lean into it, just like a regular bike." The fact that the streamliner rides so well speaks volumes about Wheeler's engineering skills: "I'm no daredevil--I won't jump into something that doesn't ride well."
Wheeler estimates around 8000 total hours of work were put into the EZ Hook streamliner, by some very dedicated people. "Phelps Wood has been extremely supportive of the whole deal, and guys like Doug Meyer, Elliott Andrews, Bill Ocheltree, Ron Howe and Frank Sherrill have helped immeasurably," says Wheeler gratefully. And the soft-spoken engineer has even loftier goals than the existing motorcycle speed record itself: "According to our calculations, with the right kind of horsepower and conditions, 400 mph isn't out of reach." Well, with his kind of top-speed savvy, one thing's for sure: When the usual speed-hungry hordes descend on Bonneville this July, we'll be puttin' our money on Sam Wheeler.
Bonneville blasting with Doug Meyer
Sport Rider asked me, "What are some important things to consider when running top speed?" The answer is everything. After nearly 20 years of running at the Bonneville Salt Flats, I've come to appreciate how important the little things are, and how quickly things can get ugly. Everything needs to be looked at carefully because speed magnifies problems. An annoyance at 100 mph can become terrifying at 180.
Doug Meyer has been running...
Doug Meyer has been running motorcycles at the Bonneville Salt Flats for over 20 years. He has set 13 records on seven different Kawasakis and currently holds six records. His ZX-11 has gone just under 197 mph, and he continues to chase that very elusive 200-mph-club membership. Doug can be reached at Muzzys in Bend, Oregon.
The obvious items to double-check are wheel alignment, steering-head bearings, swingarm pivot bushings, tire condition, rating and pressure. Steering dampers are an absolute must. (At Bonneville they're required for any bike that runs over 125 mph.) Steering-head bearings that are too loose or too tight can aggravate weaves and wobbles as well.
Wheel alignment is critical in several ways. The centerline of both wheels must be in line, and they must also be centered with the steering axis and the chassis. This is checked by setting the chassis with wheels (but no tires) up on stands. Then using levels, strings, a wheel-alignment tool and plumb bobs I determine any errors. Using new spacers or shims brings everything into alignment. This really pays off in stability.
The steering-head bearings shouldn't have any play, and should be just tight enough to allow the forks to move on their own all the way to one side when given a push with the front wheel off the ground. Tires should be V-rated, of course. Be aware that a cold tire can overheat in the center of the tread and fail when subjected to a run at top speed. Check for adequate clearance between the tires and body of chassis parts. Tires grow slightly at speed. When you do a top-speed run, your engine is experiencing stresses greater than at any other time. Oil may blow out the crankcase vent and gaskets may weep. Check everything carefully. Remember, the first time you go very fast on your bike may be the first time your bike has ever gone that fast. Don't do anything suddenly, especially getting off and on the throttle. Roll off gently.
The faster you go, the greater the role of aerodynamics. Your body becomes a moveable aerodynamic device. Your elbows, the curve of your back, the placement of your helmet behind the screen can all have an effect on speed and handling.
Finally, let me say that, after riding over a thousand miles at speeds approaching 200 mph, I would never do this on the street. A ZX-11 or CBR1100XX are both capable of running a sustained 175 mph. At 175 mph, you cover 256 feet per second. On most roads, you are less then 20 feet from the ditch. On the salt flats the course is 120 feet wide, and I have had a crosswind blow me completely off the course at 190 mph. Think about it.
This article was originally published in the April 1997 issue of Sport Rider.